EASA SIB 2007-35
FAA SAIB CE-07-46 - Installation of Bulkhead Universal Fittings in a Hydraulic Pump Port
Summary
FAA Special Airworthiness Information Bulletin CE-07-46 is an informational bulletin addressing an airworthiness concern related to the installation of bulkhead universal fittings in hydraulic pump ports. It highlights issues with improper installation causing hydraulic fluid leaks due to o-ring damage. This bulletin applies to any aircraft equipped with these bulkhead universal fittings and references standards for proper installation.
What Changed
This bulletin introduces guidance on the correct installation of bulkhead universal fittings, emphasizing the use of AN6289 nuts with backup retainers instead of AN924 nuts for new or modified installations. It clarifies that improper installation can lead to o-ring damage and hydraulic leaks, and it references superseded standards that no longer support the use of AN924 nuts in certain applications.
Why It Matters
Proper installation of bulkhead universal fittings is critical to prevent hydraulic fluid leaks which can compromise aircraft safety and system reliability. Operators, maintenance organizations, and compliance teams must understand the correct hardware and installation procedures to avoid costly repairs and ensure continued airworthiness. This bulletin helps prevent failures in medium and high-pressure hydraulic systems by promoting adherence to updated installation standards.
What To Do
Stakeholders should verify the correct nut type—AN6289 with MS28773 backup retainer versus AN924—before installation using current parts catalogs and service bulletins. Installations must follow the manufacturer's instructions or applicable SAE Aerospace Standards such as MS21344 or MS33566. Substituting an AN924 nut for an AN6289 nut without approval is not recommended, and existing installations with AN924 nuts should be reviewed for performance adequacy.
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